Fe450 suspension upgrade

I am you height and my weight in the sauna is 83 kg, much more with equipment and mud. I put 80 spring on the shock and 4.7 springs in the forks and it was night and day to the better. The stiffer spring on the shock made a big difference as now the front wheel has better grip and the forks can work as intended. Ofcourse the clickers are adjusted for the new springs too.

I have talked to some really good guys and they told me that in general the springs are too soft to suit the beginner and the reporter testing the bike. Then the ride should be plush, soft and nice. But as soon as you pick up speed it's too soft and the handling suffers.
Ofcourse this is also about personal preference, but the change made a huuge difference for me.

So to sum it up. Check the bikes sag and geometry, make sure you have stiff enough springs to support it all. As you are heavier then I am, I'm sure you need even stiffer springs.
The guy that helped me told me that one need to go one higher on the shock than KTM recommends. He also told me that it's very important that the bikes suspension is equal over the front and back. So if you hold the bike up and push down on the foot peg it should go down and then up the same distance and at the same speed both in front and at the back. In general most bikes sag more at the back wheel, changing the bikes geometry.

Good luck!

And remember, I am only one of all "internet experts" knowing "this and that" Read up, talk to people and test different things yourself. What I told you helped me and the guy helping me is doing good on competitions, so I hope you have something to start with.